Dawn had just broken the following day when Don Winslow sat up on the edge of his berth. There was a light of determination in his eye, and a fighting set to his unshaven jaw.

He was going to get up, shave and dress before the ship’s doctor had a chance to forbid him. He was tired of lying in a berth. Most of all, he was anxious to see for himself if Mercedes and the others were really getting over the effects of the poison gas.

There were some difficulties to be met, of course. In the first place, his head was still woozy, and the deck heaved up and down as if in heavy weather. In the second place, someone had taken away his torn and muddy uniform. If he could get to the locker in the corner, though, he might find something to put on.

Groping his way along the bulkhead, Don reached the locker and jerked open the door. There, as he had hoped, hung an officer’s spare uniform, along with a dress sword, weapon belt and other equipment. A drawer beneath contained underwear, shaving kit, and towels.

The set-up was complete, including a hot water tap in another corner of the cabin. If only Red didn’t wake up, or the doctor come in before he was dressed....

Fifteen minutes later Don was buttoning up his borrowed tunic, when a sudden yell and a thump spun him around in alarm.

“Sufferin’ sea serpents!” gurgled the voice of Red Pennington.

More muffled groans, grunts and howls for help issued from the tangle of bedclothes under Red’s berth. Don came to the rescue, laughing so hard that he almost lost his footing.

“Boy! You sure hit the deck in a hurry!” he chuckled, unwinding a sheet from around his stocky friend’s neck. “What were you dreaming about, anyway, to make you yell like that?”

“A-argh! Umph!” groaned Red, feeling of his chafed neck. “It’s no laughing matter, if you want to know it! I dreamed the Scorpion’s men were hanging me to the yardarm, and you came along just in time to cut me down. What if it was only a sheet instead of a rope? That dream was real enough!”

“It probably was,” agreed Don Winslow, his grin fading. “I had nightmares aplenty myself. It must be the effects of that poison wearing off. You’ll feel better if you get up and shave, Red. Unfortunately, I have on the only uniform in the cabin....”

“Unfortunately is right,—if you refer to the fit!” cut in the fat lieutenant sourly as he got to his feet. “That tunic you’ve got on was built for a man of ample girth. Like me, for instance! And as for the pants—Whee-ew! Don’t let the wind catch ’em unfurled, when you go topside, Commander! That’s all I say!”

“And it’ll be enough, too, Lieutenant. At least until I get my own clothes back!” retorted Don, moving over to the open porthole. “Anyhow, this suit covers me better than—Whoa, there! Careful, sailor! Those knees of yours are going to buckle right under you!”

Catching Red’s arm, Don Winslow steadied him just in time.

“Where were you going to walk to, shipmate?” he asked.

Pennington’s reply was shaky, despite his plucky grin.

“Across to that chair and then collapse!” he answered. “Boy, oh, boy—this room’s going around! I’m weak as a baby. Hope it’ll pass off before Doc orders me back to bed.”

“Hope so, Red!” replied Don, easing his friend into the chair. “We’ll just sit here and talk for a few minutes. You know, I wish Headquarters hadn’t ordered us to destroy the Scorpion’s base, here. I hate to blow up all the machinery there that’s too heavy to move. If only I had another month to study those new inventions!”

“Okay, Commander!” chuckled Red Pennington. “Why don’t you dig up the whole underground base and take it along as a souvenir? That’d be just as reasonable as—Say, listen, Skipper! You ought to be more than satisfied with what you’ve done already. Wasn’t it you that found the Scorpion’s base, to begin with? And who else but Don Winslow discovered how our ships were destroyed, here in the Windward Passage? It was you, more than anybody else, who pulled the last trick of sinking the Scorpion’s submarine. What more do you want, to be happy?”

Don Winslow turned to gaze out of the porthole at the sunlit waves of the cove. Beyond stretched the white sand beach, now swarming with sailors in dungarees.

The Gatoon’s launch and two whaleboats were pulled up at the edge of the water. Don guessed that they were getting ready to blow up the great steel cylinder buried at the jungle’s edge. In a few hours, at most, the gunboat would be weighing anchor, bound for the safety of civilized ports.

Which was all as it should be; and yet....

“If the truth has to be told, Red,” the young commander said softly, “I’ll never be satisfied until I nab the biggest prize of all—the Scorpion himself. Anything less than wiping out that menace to world peace, falls short of victory. You know how deeply I feel about that!”

“I do; and you’re not alone in that feeling!” responded Pennington earnestly. “But remember, Skipper, the capture of the Scorpion is nearer today than it was six months ago. Through your efforts his secret organization is now on the defensive—almost on the run. I may not be a prophet or anything like that, but I’ll bet my life that within six months’ time you’ll have the Scorpion across the table from you—a prisoner!”

For a long moment Don Winslow gazed straight into his friend’s eager face. Red’s praise, his confidence, his enthusiasm, were all exaggerated, perhaps. All the same they meant a lot just at this time. The young commander’s chest expanded with a sigh of unspoken gratitude to this loyal friend and shipmate.

“You’re sure a grand tonic, Red, old man!” he smiled. “I hope your prediction comes true, to the letter. But we’ve got to do something more than just hope and wish, you know!”

“I do know, Don!” replied the chubby officer soberly. “And I’ve been doing a lot of thinking in the last few hours. There’s an idea that came to me last night. Maybe you’ll say it’s all crazy, but....”

“Crazy ideas are sometimes the best, after all, Red,” Don encouraged, as Pennington hesitated. “Let’s have it, anyhow. We can’t afford to overlook any bets in this man’s game, so shoot!”

Red Pennington wriggled uneasily in his chair.

“Well—all right. You asked for it, so don’t laugh!” he blurted finally. “It’s just this: you know enough right now to pass yourself off as one of the Scorpion’s agents. You actually did it, for a short while, the time we barged in on Shilling and the Shark,—remember? Why couldn’t you do it again, and make it stick?”

Don Winslow took a turn up and down the cabin’s narrow space, frowning as he chewed mentally on Red’s suggestion. Bringing up before his friend’s chair, he shook his head smilingly.

“It wouldn’t do, shipmate,” he stated. “In the first place, we’d have to capture some member of Scorpia who looked enough like me to make my disguise and substitution possible. Next, I’d have to find a way to open that man’s mind out flat, and memorize everything he knew. It’s all very well to dream about, but you know yourself such breaks only come once in a lifetime.”

“Unless you make ’em, Skipper!” returned the stocky lieutenant, pushing himself up to his feet. “For instance, you could get yourself kicked out of the Navy—dishonorably discharged—stripped of your commission—disgraced publicly before your shipmates. Suppose you did that, and were determined to get revenge on the Navy for breaking you. Just where, then, would you be most likely to turn for help? Answer me, Don!”

For ten seconds the young commander stood gaping in stark amazement at the wildness of Red Pennington’s scheme. Slowly his expression changed to a boyish grin.

“I get you now, Red!” he said admiringly. “For sheer, crazy daring, your idea takes the cake. It’s fantastic, goofy, impossible, and yet—the more I think about it the more it grows on me, sailor! We’ll talk it over with Michael Splendor in any case, and see....”

With a sudden leap, Don Winslow cleared the space to the cabin door and yanked it violently open. A crouched figure outside dodged back, ducking around a corner. The officer sprang after him, only to trip and go sprawling in the “cabin country” just outside.

Ruefully he got to his feet and re-entered the door, closing it after him.

“Looks as if that poison gas left my legs kind of wobbly, too!” he grumbled, seating himself on his berth. “I almost caught Mr. Snooper at that. But, Red! You see what this means? There’s at least one Scorpion spy aboard this vessel! He probably got an earful of our conversation, too, and....”

“BOO-OOM! BR-ROM-BOOM!”

The heavy explosions came from somewhere inshore. Red Pennington leaped from his chair to join Don Winslow at the cabin’s porthole. They were in time to see a huge mushroom of earth and water rise high over the jungle at the edge of the little cove.

Closer to the ship, and traveling nearer at appalling speed, rose a low wall of water—a miniature tidal wave created by the blast. As it struck the Gatoon’s port bow, the decks tilted crazily, like those of a toy boat. After the wave had passed there came a dull roar of water rushing into a vast crater in the cove’s white beach.

“The underground base!” breathed Red, clinging weakly to the porthole. “They’ve blown it up, Don, along with all that machinery the Scorpion’s agents left behind!”